High-performance affinity chromatography with immobilization of protein A and L-histidine on molded monolith

Lectin Purification through Affinity Chromatography Exploiting Macroporous Monolithic Adsorbents

Growing medical, engineering, biochemical, and biological interest has led to a steady pace of research and development into polymeric monolithic structures with densely interconnected pores for purifying bio compounds. Cryogels, which are generated by freezing a reactive polymerization mixture, are highlighted due to their versatility and low relative cost as macroporous, polymeric, monolithic adsorbents. The conversion of cryogels into affinity adsorbents is one possible alternative to their optimal application. Some of the most often utilized supports for immobilizing particular ligands are monolithic columns manufactured with epoxy radicals on their surfaces. The purification of biomolecules with a high degree of specificity, such as lectins and glycoproteins with an affinity for glycosylated groups, has garnered interest in the use of fixed non-traditional beds functionalized with ligands of particular interest. The interaction is both robust enough to permit the adsorption of glycoproteins and reversible enough to permit the dissociation of molecules in response to changes in the solution’s pH. When compared to other protein A-based approaches, this one has been shown to be more advantageous than its counterparts in terms of specificity, ease of use, and cost-effectiveness. Information on polymeric, macroporous, monolithic adsorbents used in the affinity chromatographic purification of lectins has been published and explored.

Affinity monolith chromatography: A review of general principles and recent developments

Affinity monolith chromatography (AMC) is a liquid chromatographic technique that utilizes a monolithic support with a biological ligand or related binding agent to isolate, enrich, or detect a target analyte in a complex matrix. The target-specific interaction exhibited by the binding agents makes AMC attractive for the separation or detection of a wide range of compounds. This article will review the basic principles of AMC and recent developments in this field. The supports used in AMC will be discussed, including organic, inorganic, hybrid, carbohydrate, and cryogel monoliths. Schemes for attaching binding agents to these monoliths will be examined as well, such as covalent immobilization, biospecific adsorption, entrapment, molecular imprinting, and coordination methods. An overview will then be given of binding agents that have recently been used in AMC, along with their applications. These applications will include bioaffinity chromatography, immunoaffinity chromatography, immobilized metal-ion affinity chromatography, and dye-ligand or biomimetic affinity chromatography. The use of AMC in chiral separations and biointeraction studies will also be discussed.

Ligand fishing via a monolithic column coated with white blood cell membranes: A useful technique for screening active compounds in Astractylodes lancea

The cell membrane-coated monolithic column (CMMC) ligand fishing assay is an interesting approach set up for the study of natural products (NPs). NPs such as Atractylodes lancea contain many compounds. Traditional methods used to separate compounds and determine active compounds by pharmacological tests are time-consuming and inefficient. Therefore, an alternative method is required to determine active compounds in NPs. Here, white blood cells were broken, and the white blood cell membranes (WBCMs) were immobilized on the surface of a monolithic column to form a CMMC. The column was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy. Combined with gas chromatography/mass spectrometry (GC/MS), the CMMC was used to screen active compounds in Atractylodes lancea. Three potential active compounds including hinesol, β-eudesmol, and 4-phenylbenzaldehyde were discovered. A molecular docking assay demonstrated that these compounds could bind to MD-2 laid on WBCMs. In addition, antiinflammatory effects by the discovered compound in vitro were confirmed, and β-eudesmol showed a concentration-dependent inhibitory effect on the tumor necrosis factor (TNF)-α of a RAW264.7 cell (P < 0.05). The CMMC ligand fishing assay exhibits good selectivity, great speed effects and is a potentially reliable tool for drug discovery in NPs.

Amino acid-based hydrophobic affinity cryogel for protein purification from ora-pro-nobis (Pereskia aculeata Miller) leaves

The surfaces of the polyacrylamide cryogels were coated with L-tryptophan (cryogel-Trp) or L-phenylalanine (cryogel-Phe) to enhance crude leaf extract-derived ora-pro-nobis (OPN) protein binding via pseudo-specific hydrophobic interactions. Cryogels functionalized with amino acids were prepared and characterized through morphological, hydrodynamic, and thermal analyses. The adsorption capacities of cryogel-Phe and cryogel-Trp were evaluated in terms of type (sodium sulfate or sodium phosphate) and concentration (0.02 or 0.10 mol∙L^-1) of saline solution, pH (4.0, 5.5, or 7.0), and NaCl concentration (0.0 or 0.5 mol∙L^-1). The cryogel-Phe presented a higher adsorptive capacity, achieving its maximum value (q = 92.53 mg∙g^-1) when the crude OPN crude leaf extract was diluted in sodium sulfate 0.02 mol∙L^-1 + NaCl 0.50 mol∙L^-1, at pH = 7.0. The dilution rate significantly (p < 0.05) affected the recovered protein amount after the adsorption and elution processes, reaching 94.45% when the feedstock solution was prepared with a crude extract 5 times. The zeta potential for the eluted OPN proteins was 5.76 mV (pH = 3.23) for both dilution rates. The secondary structure composition mainly included β-sheets (46.50%) and α-helices (13.93%). The cryogel-Phe exhibited interconnected pores ranging 20-300 μm in size, with a Young modulus of 1.51 MPa, and thermal degradation started at 230 °C. These results indicate that the cryogel-Phe exhibited satisfactory properties as promising chromatography support for use in high-throughput purification of crude leaf extract-derived OPN proteins.

An insight into chiral monolithic stationary phases for enantioselective high-performance liquid chromatography applications

In this review, three main classes of chiral monolithic stationary phases, namely silica-, organic polymer-, and hybrid-based monolithic stationary phases, are covered. Their preparations, applications, and advantages compared with the conventional-packed and open-tubular capillary columns are discussed. A detailed description of the different types and techniques used for the introduction of chiral selectors into the monolithic matrices such as immobilization, functionalization, coating, encapsulation, and bonding. Special emphasis is given to the recent developments of chiral selectors in HPLC monolithic stationary phases during the past 18 years.

Monolith affinity chromatography for the rapid quantification of a single-chain variable fragment immunotoxin

We developed a novel analytical method for concentration determination of tandem single‐chain antibody diphtheria toxin (immunotoxin). The method is based on polymethacrylate monoliths with Protein L ligands as the binding moiety. Different buffers were tested for elution of the Protein L‐bound immunotoxin and 4.5 M guanidinium hydrochloride performed best. We optimized the elution conditions and the method sequence resulting in a fast and robust method with a runtime <10 min. Fast determination of immunotoxin is critical if any process decisions rely on this data. We determined method performance and a lower limit of detection of 27 μg/mL and a lower limit of quantification of 90 μg/mL was achieved. The validity of the method in terms of residual analysis, precision, and repeatability was proven in a range from 100 to 375 μg/mL. The short runtime and ease of use of a high‐performance liquid chromatography method is especially useful for a process analytical tool approach. Bioprocesses related to immunotoxin where fermentation or other process parameters can be adjusted in accordance to the immunotoxin levels will be benefited from this method to achieve the highest possible purity and productivity.

Affinity monolith chromatography: A review of general principles and applications

Affinity monolith chromatography, or AMC, is a liquid chromatographic method in which the support is a monolith and the stationary phase is a biological-binding agent or related mimic. AMC has become popular for the isolation of biochemicals, for the measurement of various analytes, and for studying biological interactions. This review will examine the principles and applications of AMC. The materials that have been used to prepare AMC columns will be discussed, which have included various organic polymers, silica, agarose, and cryogels. Immobilization schemes that have been used in AMC will also be considered. Various binding agents and applications that have been reported for AMC will then be described. These applications will include the use of AMC for bioaffinity chromatography, immunoaffinity chromatography, dye-ligand affinity chromatography, and immobilized metal-ion affinity chromatography. The use of AMC with chiral stationary phases and as a tool to characterize biological interactions will also be examined.

New platform for simple and rapid protein-based affinity reactions

We developed a spongy-like porous polymer (spongy monolith) consisting of poly(ethylene-co-glycidyl methacrylate) with continuous macropores that allowed efficient in situ reaction between the epoxy groups and proteins of interest. Immobilization of protein A on the spongy monolith enabled high-yield collection of immunoglobulin G (IgG) from cell culture supernatant even at a high flow rate. In addition, immobilization of pepsin on the spongy monolith enabled efficient online digestion at a high flow rate.

Affinity chromatography: A versatile technique for antibody purification

Antibodies continue to be extremely utilized entities in myriad applications including basic research, imaging, targeted delivery, chromatography, diagnostics, and therapeutics. At production stage, antibodies are generally present in complex matrices and most of their intended applications necessitate purification. Antibody purification has always been a major bottleneck in downstream processing of antibodies, due to the need of high quality products and associated high costs. Over the years, extensive research has focused on finding better purification methodologies to overcome this holdup. Among a plethora of different techniques, affinity chromatography is one of the most selective, rapid and easy method for antibody purification. This review aims to provide a detailed overview on affinity chromatography and the components involved in purification. An array of support matrices along with various classes of affinity ligands detailing their underlying working principles, together with the advantages and limitations of each system in purifying different types of antibodies, accompanying recent developments and important practical methodological considerations to optimize purification procedure are discussed.

Antibody purification via affinity membrane chromatography method utilizing nucleotide binding site targeting with a small molecule

Here, we present an affinity membrane chromatography technique for purification of monoclonal and polyclonal antibodies from cell culture media of hybridomas and ascites fluids. The m-NBST method utilizes the nucleotide-binding site (NBS) that is located on the Fab variable domain of immunoglobulins to enable capturing of antibody molecules on a membrane affinity column via a small molecule, tryptamine, which has a moderate binding affinity to the NBS. Regenerated cellulose membrane was selected as a matrix due to multiple advantages over traditionally used resin-based affinity systems. Rituximab was used for proof of concept experiments. Antibody purification was accomplished by first capture of injected samples while running equilibration buffer (50 mM sodium phosphate pH 7.0), followed by elution achieved by running a gradient of mild elution buffer (3 M NaCl in 50 mM phosphate pH 7.0). The results indicate that the m-NBST column efficiency for Rituximab was >98%, with a purity level of >98%. The quality and the capacity of this small molecule membrane affinity purification method is further evaluated for a number of parameters such as: injection concentrations, volumes, wash/bind time, elution gradient, antibody/protein-contaminant combinations, effects of injection buffer, post-purification antigen binding activity of antibodies, and column reusability and stability.

Affinity monolith chromatography: a review of principles and recent analytical applications

Affinity monolith chromatography (AMC) is a type of liquid chromatography that uses a monolithic support and a biologically related binding agent as a stationary phase. AMC is a powerful method for the selective separation, analysis, or study of specific target compounds in a sample. This review discusses the basic principles of AMC and recent developments and applications of this method, with particular emphasis being given to work that has appeared in the last 5 years. Various materials that have been used to prepare columns for AMC are examined, including organic monoliths, silica monoliths, agarose monoliths, and cryogels. These supports have been used in AMC for formats that have ranged from traditional columns to disks, microcolumns, and capillaries. Many binding agents have also been employed in AMC, such as antibodies, enzymes, proteins, lectins, immobilized metal ions, and dyes. Some applications that have been reported with these binding agents in AMC are bioaffinity chromatography, immunoaffinity chromatography or immunoextraction, immobilized-metal-ion affinity chromatography, dye-ligand affinity chromatography, chiral separations, and biointeraction studies. Examples are presented from fields that include analytical chemistry, pharmaceutical analysis, clinical testing, and biotechnology. Current trends and possible directions in AMC are also discussed.

Identifying analytics for high throughput bioprocess development studies

In recent years, high throughput screening (HTS) studies have been increasingly employed as an integral element of bioprocess development activities. These studies are often limited by an analytical bottleneck; they generate multiple samples for analysis and the available analytical methods cannot always cope with the added analytical burden. A potential solution to this challenge is offered by the deployment of appropriate analytics. This article outlines features of analytical methods that affect their fit to high throughput (HT) applications. These are discussed for a range of analytics frequently used in bioprocess development studies of monoclonal antibodies. It then outlines how these features need to be considered in order to classify analytical methods in terms of their particular application in high throughput scenarios.

Production of human anti-glycophorin-A monoclonal antibodies and their purification by pseudoaffinity chromatography using a convective interaction media monolithic column

Monoclonal antibodies (MAbs) against glycophorin-A (GPA) could be used in identifying MN blood groups, detecting specific markers of erythroid differentiation, and studying parasite interactions. Large-scale production of MAbs in bioreactors demands an efficient and rapid separation technology. The present study describes the production of a human anti-GPA monoclonal antibody and its purification using a pseudo-bioaffinity L-histidine-convective interaction media (CIM) monolithic column. Hybridomas were generated by fusion of mouse myeloma cell line (Sp2/0) and spleen cells from the mouse immunized with Triton X-100 solubilized RBC membrane proteins. Hybridomas producing antibodies specific to commercial glycophorin-A were screened by indirect enzyme-linked immunosorbent assay (ELISA). The antibodies produced by the stable clones were found to be IgG1 with kappa light chain. Purification of IgG1 MAbs from the cell culture supernatant carried out with a CIM-EDA-histidine disk resulted in high specific activity with purification fold of 8.3 in the fraction eluted with MOPS buffer containing 0.2 M NaCl. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and ELISA showed that the antibodies obtained were highly pure, with high antigen-binding efficiency. The results indicate that faster separation and efficient recovery of high-purity anti-GPA MAbs could be achieved by using CIM-EDA-histidine disk.

Bioaffinity chromatography on monolithic supports

Affinity chromatography on monolithic supports is a powerful analytical chemical platform because it allows for fast analyses, small sample volumes, strong enrichment of trace biomarkers and applications in microchips. In this review, the recent research using monolithic materials in the field of bioaffinity chromatography (including immunochromatography) is summarized and discussed. After giving an introduction into affinity chromatography, information on different biomolecules (antibodies, enzymes, lectins, aptamers) that can act as ligands in bioaffinity chromatography is presented. Subsequently, the history of monoliths, their advantages, preparation and formats (disks, capillaries and microchips) as well as ligand immobilization techniques are mentioned. Finally, analytical and preparative applications of bioaffinity chromatography on monoliths are presented. During the last four years 37 papers appeared. Protein A and G are still most often used as ligands for the enrichment of immunoglobulins. Antibodies and lectins remain popular for the analysis of mainly smaller molecules and saccharides, respectively. The highly porous cryogels modified with ligands are applied for the sorting of different cells or bacteria. New is the application of aptamers and phages as ligands on monoliths. Convective interaction media (epoxy CIM disks) are currently the most used format in monolithic bioaffinity chromatography.

Versatility of polymethacrylate monoliths for chromatographic purification of biomolecules

Polymethacrylate monoliths, specifically poly(glycidyl methacrylate-co-ethylene dimethacrylate) or poly(GMA-co-EDMA) monoliths, are a new generation of chromatographic supports and are significantly different from conventional particle-based adsorbents, membranes, and other monolithic supports for biomolecule purification. Similar to other monoliths, polymethacrylate monoliths possess large pores which allow convective flow of mobile phase and result in high flow rates at reduced pressure drop, unlike particulate supports. The simplicity of the adsorbent synthesis, pH resistance, and the ease and flexibility of tailoring their pore size to that of the target biomolecule are the key properties which differentiate polymethacrylate monoliths from other monoliths. Polymethacrylate monoliths are endowed with reactive epoxy groups for easy functionalization (with anion-exchange, hydrophobic, and affinity ligands) and high ligand retention. In this review, the structure and performance of polymethacrylate monoliths for chromatographic purification of biomolecules are evaluated and compared to those of other supports. The development and use of polymethacrylate monoliths for research applications have grown rapidly in recent times and have enabled the achievement of high through-put biomolecule purification on semi-preparative and preparative scales.

Collecting peptide release from the brain using porous polymer monolith-based solid phase extraction capillaries

Porous polymer monolithic (PPM) columns are employed to collect and concentrate neuronal release from invertebrate and vertebrate model systems, prior to their characterization with mass spectrometry. The monoliths are fabricated in fused-silica capillaries from lauryl methacrylate (LMA) and ethylene glycol dimethacrylate (EDMA). The binding capacities for fluorescein and for fluorescently labeled peptides are on the order of nanomoles per millimeter of length of monolith material for a capillary with an inner diameter of 200 microm. To evaluate this strategy for collecting peptides from physiological solutions, angiotensin I and insulin in artificial seawater are loaded onto, and then released from, the monoliths after a desalination rinse, resulting in femtomole limits of detection via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Positioned in the extracellular media near Aplysia californica bag cell neurons, upon electrical stimulation, these LMA-EDMA monoliths are also used to collect and concentrate peptide release, with egg-laying hormones and acidic peptide detected. In addition, the collection of several known peptides secreted from chemically stimulated mouse brain slices demonstrates their ability to collect releasates from a variety of neuronal tissues. When compared to collection approaches using individual beads placed on brain slices, the PPM capillaries offer greater binding capacity. Moreover, they maintain higher spatial resolution, compared to the larger-volume, solid-phase extraction collection strategies.

Development of an affinity silica monolith containing human serum albumin for chiral separations

An affinity monolith based on silica and containing immobilized human serum albumin (HSA) was developed and evaluated in terms of its binding, efficiency and selectivity in chiral separations. The results were compared with data obtained for the same protein when used as a chiral stationary phase with HPLC-grade silica particles or a monolith based on a copolymer of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA). The surface coverage of HSA in the silica monolith was similar to values obtained with silica particles and a GMA/EDMA monolith. However, the higher surface area of the silica monolith gave a material that contained 1.3-2.2-times more immobilized HSA per unit volume when compared to silica particles or a GMA/EDMA monolith. The retention, efficiency and resolving power of the HSA silica monolith were evaluated using two chiral analytes: d/l-tryptophan and R/S-warfarin. The separation of R- and S-ibuprofen was also considered. The HSA silica monolith gave higher retention and higher or comparable resolution and efficiency when compared with HSA columns that contained silica particles or a GMA/EDMA monolith. The silica monolith also gave lower back pressures and separation impedances than these other materials. It was concluded that silica monoliths can be valuable alternatives to silica particles or GMA/EDMA monoliths when used with immobilized HSA as a chiral stationary phase.

Affinity-based methodologies and ligands for antibody purification: Advances and perspectives

Many successful, recent therapies for life-threatening diseases such as cancer and rheumatoid arthritis are based on the recognition between native or genetically engineered antibodies and cell-surface receptors. Although naturally produced by the immune system, the need for antibodies with unique specificities and designed for single application, has encouraged the search for novel antibody purification strategies. The availability of these products to the end-consumer is strictly related to manufacture costs, particularly those attributed to downstream processing. Over the last decades, academia and industry have developed different types of interactions and separation techniques for antibody purification, affinity-based strategies being the most common and efficient methodologies. The affinity ligands utilized range from biological to synthetic designed molecules with enhanced resistance and stability. Despite the successes achieved, the purification "paradigm" still moves interests and efforts in the continuous demand for improved separation performances. This review will focus on recent advances and perspectives in antibody purification by affinity interactions using different techniques, with particular emphasis on affinity chromatography.

Development of sulfhydryl-reactive silica for protein immobilization in high-performance affinity chromatography

Two techniques were developed for the immobilization of proteins and other ligands to silica through sulfhydryl groups. These methods made use of maleimide-activated silica (the SMCC method) or iodoacetyl-activated silica (the SIA method). The resulting supports were tested for use in high-performance affinity chromatography by employing human serum albumin (HSA) as a model protein. Studies with normal and iodoacetamide-modified HSA indicated that these methods had a high selectivity for sulfhydryl groups on this protein, which accounted for the coupling of 77-81% of this protein to maleimide- or iodoacetyl-activated silica. These supports were also evaluated in terms of their total protein content, binding capacity, specific activity, nonspecific binding, stability, and chiral selectivity for several test solutes. HSA columns prepared using maleimide-activated silica gave the best overall results for these properties when compared to HSA that had been immobilized to silica through the Schiff base method (i.e., an amine-based coupling technique). A key advantage of the supports developed in this work is that they offer the potential of giving greater site-selective immobilization and ligand activity than amine-based coupling methods. These features make these supports attractive in the development of protein columns for such applications as the study of biological interactions and chiral separations.

Affinity monoliths for ultrafast immunoextraction

Affinity monoliths based on a copolymer of glycidyl methacrylate and ethylene dimethacrylate were developed for ultrafast immunoextractions. Rabbit immunoglobulin G (IgG) and anti-FITC antibodies were used as model ligands for this work. The antibody content of the monoliths was optimized by varying both the polymerization and immobilization conditions for preparing such supports. The temperature and porogen composition used during polymerization showed significant effects on monolith morphology and on the amount of antibodies that could be coupled to these materials. The effects of various immobilization procedures and coupling conditions were also evaluated, including the coupling temperature, pH, protein concentration, and use of high buffer concentrations. The maximum ligand density obtained for rabbit IgG was approximately 60 mg/g. When a 4.5 mm i.d. x 0.95 mm monolith disk containing anti-FITC antibodies was used, 95% extraction of fluorescein was achieved in 100 ms. These properties make such monoliths attractive for work in the rapid isolation of analytes from biological samples. Similar columns can be developed for other targets by varying the types of antibodies or binding agents placed within the monoliths.

Future of antibody purification

Antibody purification seems to be safely ensconced in a platform, now well-established by way of multiple commercialized antibody processes. However, natural evolution compels us to peer into the future. This is driven not only by a large, projected increase in the number of antibody therapies, but also by dramatic improvements in upstream productivity, and process economics. Although disruptive technologies have yet escaped downstream processes, evolution of the so-called platform is already evident in antibody processes in late-stage development. Here we perform a wide survey of technologies that are competing to be part of that platform, and provide our [inherently dangerous] assessment of those that have the most promise.